Satellite imagery reveals two formations near Anak Krakatau after prolonged September eruptions.
Indonesia’s Anak Krakatau is physically changing again, with satellite imagery showing a larger volcanic island and two newly detected land formations following intense eruptions in September.
Volcano Expands by 32.8 Hectares
Indonesia’s Geology Agency said Anak Krakatau expanded by 32.8 hectares, or around 81 acres, after recent eruptions produced lava flows. The increase was identified by comparing Sentinel satellite imagery taken on August 8 and September 15, showing how the volcano’s surface changed during the eruption period.
Eruption Continues for 25 Hours
Anak Krakatau erupted for about 25 hours from September 4 to September 6, sending lava toward the northwest, west and southwest. The activity added new volcanic material around the island and contributed to the measurable increase in its land area.
Two New Formations Detected Nearby
Sentinel imagery from September 23 detected two additional land formations near the volcano. One was located around 760 meters northwest of Anak Krakatau’s coastline, while the other was approximately 495 meters southeast, placing the formations on opposite sides of the volcano.
Scientists Need More Data to Explain Formations
The Geology Agency said the two formations may be connected to the September eruptions, but more recent data and further analysis are needed before scientists can determine whether they represent new eruption centers. Authorities have therefore not yet reached a final conclusion about how the formations developed.
Eruptions Disrupt Thousands of Flights
The eruptions also sent volcanic ash over Jakarta and surrounding areas, forcing several airports to close. More than 340,000 travelers were affected, with 2,961 flights canceled, delayed or diverted. Anak Krakatau is one of roughly 130 active volcanoes in Indonesia and emerged from the area once occupied by Krakatau, which was destroyed in its catastrophic 1883 eruption.
Anak Krakatau’s latest expansion shows that the volcano continues to reshape the landscape around the Sunda Strait, while the two newly detected formations remain under scientific assessment. For Indonesians, continued monitoring is important because volcanic activity can affect communities and transportation well beyond the immediate crater area. For Singaporeans traveling to Indonesia, the large number of disrupted flights also shows how major eruptions can affect regional travel networks.
Sources: Asia One (2026) , Reuters (2026)
Keywords: Anak Krakatau Eruption, Indonesia Volcano, New Land Formations, Anak Krakatau Expansion, Sentinel Satellite, Geology Agency
